1. Field of the Invention
The present invention relates to an image processing apparatus, a system, an image processing method, a calibration method, and a computer-readable recording medium.
2. Description of the Related Art
In one three-dimensional measurement technique called the stereo method, a block of pixels that is correlated with a block of pixels in an image captured with one camera is found in an image captured with another camera (points corresponding to each other are extracted), and distance data is calculated based on parallax, which indicates a relative positional difference between the two images, based on the principle of triangulation. One technique is known that uses a pattern having a lot of feature points (for example, a random pattern including irregular patterns) to increase the density of extraction of corresponding points in the aim of improving accuracy of the distance data calculation.
For example, Japanese Laid-open Patent Publication No. 2011-118328 discloses a technique for cutting out (removing) a low-frequency component contained in a random pattern in the aim of improving uniformity and dispersibility.
However, conventional techniques are configured to generate a random pattern without consideration given to the image-capturing distance (the distance between a camera and the random pattern in image capturing), and consequently are disadvantageous because of their inability to stably extract feature points.